diff --git a/essential/iwant-embedded/src/main/java/org/fluentjava/iwant/embedded/AsEmbeddedIwantUser.java b/essential/iwant-embedded/src/main/java/org/fluentjava/iwant/embedded/AsEmbeddedIwantUser.java
index c5bf0950..f4a38775 100644
--- a/essential/iwant-embedded/src/main/java/org/fluentjava/iwant/embedded/AsEmbeddedIwantUser.java
+++ b/essential/iwant-embedded/src/main/java/org/fluentjava/iwant/embedded/AsEmbeddedIwantUser.java
@@ -11,6 +11,8 @@
 import org.fluentjava.iwant.api.wsdef.WorkspaceModuleContext;
 import org.fluentjava.iwant.entry.Iwant;
 import org.fluentjava.iwant.entry3.CachesImpl;
+import org.fluentjava.iwant.entry3.DefaultUserPrefs;
+import org.fluentjava.iwant.entry3.UserPrefs;
 import org.fluentjava.iwant.entry3.WishEvaluator;
 
 /**
@@ -29,6 +31,7 @@ public static class IHavePlease {
 
 		private File wsRoot;
 		private File wsCache;
+		private UserPrefs userPrefs = new DefaultUserPrefs(null);
 
 		public IHavePlease workspaceAt(File wsRoot) {
 			this.wsRoot = wsRoot;
@@ -40,6 +43,11 @@ public IHavePlease cacheAt(File wsCache) {
 			return this;
 		}
 
+		public IHavePlease userPrefs(UserPrefs userPrefs) {
+			this.userPrefs = userPrefs;
+			return this;
+		}
+
 		public TargetOrSideEffect iwant() {
 			return new TargetOrSideEffect();
 		}
@@ -67,7 +75,7 @@ public File asPath() {
 						WsInfo wsInfo = null;
 						Caches caches = new CachesImpl(wsCache, iwantApiClasses,
 								iwant.network());
-						int workerCount = 1;
+						int workerCount = userPrefs.workerCount();
 						JavaSrcModule wsdefdefJavaModule = null;
 						JavaSrcModule wsdefJavaModule = null;
 						WorkspaceModuleContext wsdefCtx = null;
diff --git a/essential/iwant-embedded/src/test/java/org/fluentjava/iwant/embedded/AsEmbeddedIwantUserTest.java b/essential/iwant-embedded/src/test/java/org/fluentjava/iwant/embedded/AsEmbeddedIwantUserTest.java
index 0f941564..f42156bb 100644
--- a/essential/iwant-embedded/src/test/java/org/fluentjava/iwant/embedded/AsEmbeddedIwantUserTest.java
+++ b/essential/iwant-embedded/src/test/java/org/fluentjava/iwant/embedded/AsEmbeddedIwantUserTest.java
@@ -1,8 +1,15 @@
 package org.fluentjava.iwant.embedded;
 
 import java.io.File;
+import java.util.concurrent.atomic.AtomicReference;
 
+import org.fluentjava.iwant.api.core.Concatenated;
 import org.fluentjava.iwant.api.core.HelloTarget;
+import org.fluentjava.iwant.api.model.TargetEvaluationContext;
+import org.fluentjava.iwant.api.target.TargetBase;
+import org.fluentjava.iwant.coreservices.FileUtil;
+import org.fluentjava.iwant.entry.Iwant;
+import org.fluentjava.iwant.entry3.UserPrefs;
 import org.fluentjava.iwant.testarea.TestArea;
 
 import junit.framework.TestCase;
@@ -33,4 +40,68 @@ public void testHelloAsPath() {
 		assertEquals("hello message", testArea.contentOf(cached));
 	}
 
+	public void testCustomUserPrefs() {
+		class ThreadDetector extends TargetBase {
+
+			AtomicReference<String> threadName = new AtomicReference<>();
+
+			public ThreadDetector(String name) {
+				super(name);
+			}
+
+			@Override
+			protected IngredientsAndParametersDefined ingredientsAndParameters(
+					IngredientsAndParametersPlease iUse) {
+				return iUse.nothingElse();
+			}
+
+			@Override
+			public void path(TargetEvaluationContext ctx) throws Exception {
+				File dest = ctx.cached(this);
+				FileUtil.newTextFile(dest, name());
+				threadName.set(Thread.currentThread().getName());
+			}
+
+		}
+
+		ThreadDetector td1 = new ThreadDetector("td1");
+		ThreadDetector td2 = new ThreadDetector("td2");
+
+		Concatenated root = Concatenated.named("root").unixPathTo(td1)
+				.unixPathTo(td2).end();
+
+		// 1 thread only
+		UserPrefs prefsFor1 = new UserPrefs() {
+			@Override
+			public int workerCount() {
+				return 1;
+			}
+		};
+
+		AsEmbeddedIwantUser.with().userPrefs(prefsFor1).workspaceAt(wsRoot)
+				.cacheAt(cacheDir).iwant().target(root).asPath();
+		assertEquals(td1.threadName.get(), td2.threadName.get());
+
+		// 2 threads configured => td1 and td2 are built using different
+		// threads. Here we don't even care if happens always, 1 out of 20 is
+		// good enough:
+
+		UserPrefs prefsFor2 = new UserPrefs() {
+			@Override
+			public int workerCount() {
+				return 2;
+			}
+		};
+		for (int i = 0; i < 20; i++) {
+			Iwant.del(cacheDir);
+
+			AsEmbeddedIwantUser.with().userPrefs(prefsFor2).workspaceAt(wsRoot)
+					.cacheAt(cacheDir).iwant().target(root).asPath();
+			if (!td1.threadName.get().equals(td2.threadName.get())) {
+				return;
+			}
+		}
+		fail("User prefs of using 2 threads were never obeyed!");
+	}
+
 }
diff --git a/essential/iwant-entry3/src/main/java/org/fluentjava/iwant/entry3/DefaultUserPrefs.java b/essential/iwant-entry3/src/main/java/org/fluentjava/iwant/entry3/DefaultUserPrefs.java
index 492ecc8c..5f39500e 100644
--- a/essential/iwant-entry3/src/main/java/org/fluentjava/iwant/entry3/DefaultUserPrefs.java
+++ b/essential/iwant-entry3/src/main/java/org/fluentjava/iwant/entry3/DefaultUserPrefs.java
@@ -2,7 +2,7 @@
 
 import java.io.File;
 
-class DefaultUserPrefs implements UserPrefs {
+public class DefaultUserPrefs implements UserPrefs {
 
 	private final File userPrefsFile;